Method and apparatus for producing optical glasses

ABSTRACT

The invention relates to a method and an apparatus for producing optical glasses. The glasses are polished and marked, following a shaping process. The polishing and marking steps are carried out in a common processing cell which comprises a polishing station, a washing station, and a marking station.

CROSS REFERENCE TO OTHER APPLICATIONS

The present application is a divisional of U.S. application Ser. No.11/113,451, filed Apr. 22, 2005, which is a continuation of pendingInternational patent application PCT/EP2003/11827, filed Oct. 24, 2003which designates the United States and was published in German, andwhich claims priority of German patent application 102 50 856.9, filedOct. 25, 2002. The disclosure of the above application is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The invention is related to a method for producing optical glasses, inwhich the glasses are polished and marked following a shapingprocessing.

The invention, further, is related to an apparatus for producing opticalglasses, in which the glasses are polished and marked following ashaping process.

A method and an apparatus of the type specified before are known from WO01/66308 A1.

The invention will hereinafter be described with regard to anapplication for spectacle lenses. However, it goes without saying thatthe invention may also be applied for other optical glasses.

It is well known that so-called single-vision spectacle lenses aredefined by two spherical surfaces or by one spherical and one toroidalsurface. For optimising the central thickness and the peripheralthickness of single-vision spectacle lenses, a rotational symmetricaspherical function may be superimposed to the spherical or to thetoroidal surface on one of the two sides of the lens.

In contrast, so-called progressive power lenses or multifocal lenseshave at least one optical free-form surface computed by optimisationsoftware. The free-form surface is not rotationally symmetrical.Conventionally, it is located on the front surface of the spectaclelens. The so-called prescription surface, in contrast, is located on thetoroidal rear surface of the spectacle lens and is adjusted to theoptical characteristics of the spectacle user.

Plastic material progressive power lenses are produced by molding. Withthis type of production, the optical free-form surface is generatedalready during the forming process. Spectacle lenses made from silicate,in contrast, are produced by an iterative sequence of processing stepsof grinding and of polishing.

The toroidal prescription processing is executed by grinding andpolishing machines as are well known in the prior art.

The prior art, further, comprises spectacle lenses, the opticalcharacteristics of which are individually computed and optimised for anyspectacle lens. Such prior art spectacle lenses, therefore, have atleast one individually computed optical surface in a splinerepresentation. The production of such individual optical surfaces isconventionally executed for non-rotationally symmetrical plasticmaterial spectacle lenses by means of diamond lathing techniques. Suchlathes are known from WO 97/13603 as well as from EP 0 758 571 B1. Theseprior art diamond lathes operate with an automatic feeding of thespectacle lenses in connection with a conveyor belt. The spectaclelenses are affixed to blocks and are transported in ordering boxes.

When plastic material progressive power lenses are processed on theirsurface by means of a diamond lathing technology, they show a regularsurface groove structure after the completion of the lathing process.This structure is of the order of 80 to 200 nm rms surface roughness.For obtaining the necessary final roughness of less than 10 nm rms,these lathed optical surfaces must still be polished. Finally, aso-called signature has to be applied. The signature or labelling isunderstood to be a marking for product identification on the one hand.On the other hand the application of two markings on each spectacle lensmay define the optical axis, thereby assisting the optometrist to fit alens into the spectacle frame in their correct position.

As chips are generated during the polishing process, the polishedsurfaces must be cleaned from the chips and from the polishing agent andmust be dried thereafter, prior to the subsequent marking step.

A polishing machine, as may be used in the above-described context, isdescribed in WO 01/56740 A1.

In practice, for polishing lathed or ground free-form surfaces,polishing tools are used, in which a polishing surface is configured asa disposable polishing coating. The polishing surface is supported by anelastic foam structure such that the polishing surface may adapt itselfto the shape of the spectacle lens. The polishing surface is shapedeither convex or concave, depending on whether concave or convexspectacle lens surfaces shall be polished.

After each polishing process the worn disposable polishing coating isdetached from the polishing tool and is replaced by a fresh polishingcoating. Following the detachment of the worn polishing coating thepolishing tool is cleaned and dried.

During the subsequent marking of the spectacle lenses theabove-mentioned marking is conventionally applied into the spectaclelens surface pointwise, i.e. as a dot pattern, by means of a laser beam.

All of the afore-described prior art apparatuses for polishing, washingand marking have in common that the spectacle lenses are fedindividually, mostly manually.

WO 02/00392 A1 describes an apparatus for loading and for unloadingoptical work pieces. This prior art apparatus is preferably used inconnection with a grinding machine for optical single lenses. In thisprior art apparatus, the spectacle lenses are handled by means of asuction head being applied to the optical surface of the spectaclelenses. Although it is likewise suggested to use a pneumaticallyoperated three finger gripper, the latter shall, however, only be usedfor centering the spectacle lenses.

U.S. Pat. No. 6,247,999 B1 discloses a method of automaticallyexchanging polishing tools. In this prior art method a plurality ofpolishing tools is placed ready in a row on a magazine bank. A robotpicks up one of the polishing tools and attaches same to a gimballedsuspension for the polishing tool at the drive element of the polishingmachine. After completion of the polishing process the robot, togetherwith the polishing tool moves into a device in which two metal sheetsare arranged inclined with respect to the horizontal plane and enclosebetween them a gap. The robot enters the polishing tool into the gap andstrips same off there. The worn polishing tool now falls downwardly intothe inclined chute configured by the device and finally arrives at acontainer.

EP 0 567 894 A1 discloses an apparatus for guiding a work piece or atool during the processing of toroidal or of spherical surfaces ofoptical lenses on grinding or polishing machines.

In this prior art apparatus a roller bellows is located at the lowerfree end of a spindle, the bellows supporting a polishing disk. An airpressure may be generated within a volume enclosed by the rollerbellows, such that the polishing disk may be displaced axially.Moreover, the polishing disk is supported by an axially acting pistonvia a spherical joint. The roller bellows is adapted to transmit atorque for the polishing disk when rotated during operation.

This prior art apparatus has the disadvantage that the roller bellows isa relatively stiff element such that the polishing disk may effect itsproper movements only to a very limited extent.

EP 0 974 423 A1 discloses another similar polishing disk, wherein thepolishing tool may be attached to an actuator element via a bayonetjoint.

This prior art apparatus has the disadvantage that for attaching thepolishing tool, the latter must be oriented in an angularly correctorientation relative to the actuator element.

Another similar apparatus is disclosed in EP 0 974 422 A1.

BRIEF SUMMARY OF INVENTION

It is, therefore, an object underlying the present invention to furtherimprove a method and an apparatus of the type specified at the outsetsuch that the afore-mentioned problems are avoided.

In particular, it shall become possible to reduce the complexity ofproduction as is necessary according to the prior art.

In a method, specified at the outset, this object is achieved in thatthe steps of polishing and of marking are executed within a commonprocessing cell.

In an apparatus of the type specified at the outset, the object isachieved by an apparatus in which a polishing station, a washingstation, and a marking station are arranged within one common processingcell.

The object underlying the invention is thus entirely solved.

The invention namely makes it possible for the first time to concentratethe entire production process for the prescription surface following theshaping process, which conventionally is executed by lathing orgrinding, within one fully automated cell, such as to avoid thecumbersome manual work during loading and unloading of the spectacleglasses within the individual stations.

Obviously, substantial production costs may thus be saved.

In preferred embodiments of the invention the glasses are handled by thesame robot during polishing and marking.

This measure has the advantage that for all actions within theprocessing cell only one handling element is required, such thatproduction costs are also reduced insofar.

In a preferred embodiment of the inventive method it is particularlypreferred when the robot

-   -   a) takes the glasses from a conveyor belt,    -   b) feeds the glasses to a polishing station and deposits them        there,    -   c) takes a polishing tool from a tool magazine,    -   d) processes the glasses by means of the polishing tool,    -   e) deposits the polishing tool,    -   f) takes the polished glasses from the polishing station, feeds        them to a washing station and deposits them there,    -   g) picks up a washing tool,    -   h) washes the glasses in the washing station,    -   i) deposits the washing tool,    -   j) takes the washed glasses from the washing station and feeds        them to a marking station, and    -   k) takes the marked glasses from the marking station and        deposits them on the conveyor belt.

These measures have the advantage that by means of the one robot allhandling actions, i.e. conveying actions between the various stationsone the one hand as well as partly the processing steps, are assumed.

In this context it is further preferred when the robot, between theexecution of steps k) and l), executes one or more of steps a) throughi) on at least one other glass.

This measure has the advantage that the robot may operate on atime-multiplex basis, so that it may execute a handling on one glasswhile at the same time another glass is under processing otherwise, inparticular within the marking station.

In another preferred embodiment of the invention the glasses areconveyed on the conveyor belt within transportation boxes.

This measure has the advantage that the glasses may be held atpredetermined unloading and loading positions, wherein due to theirarrangement in transportation boxes the handling may be executed under adefined orientation of the glasses.

Finally, it is particularly preferred when the robot holds the glassesby means of a gripper which grips the glasses at their periphery.

This measure has the advantage that the sensitive optical surface of theglasses remains untouched, in contrast to the prior art, so that anynegative impact to these sensitive optical surfaces is made impossible.

The afore-mentioned variant of the inventive method may be still morerefined in that the glasses are gripped with a predetermined force.

It is further preferred when the glasses are conveyed in pairs.

This measure has the advantage that those glasses belonging to aparticular ordering person (patient) may be handled and conveyedtogether or directly one after another so that it may be excluded thatthey become mixed up.

It is further preferred when the glasses are arranged on a block forhandling, i.e. for conveying and for processing.

This measure has the advantage that in particular during polishing theglass itself must not be gripped.

In a particularly preferred embodiment of the inventive method apolishing tool during polishing rests with a first surface on a secondsurface of the glass, wherein the first surface is smaller than thesecond surface, the surfaces, further, being rotated in the samedirection and with essentially the same rotational speed, and whereinthe first surface is guided over the second surface, in a radialdirection. Insofar it is particularly preferred when an oscillatingmovement is superimposed on the radial movement in a directionperpendicular thereto.

In contrast to the prior art, where the polishing tool is guided overthe surface of the glass to be ground along parallel, distant paths,this feature has the advantage that no optically distinguishablepatterns are generated. Instead, a surface is generated in which thelocus of the polishing surface is no more distinguishable for the humaneye.

This holds true in particular, when the radial movement is guided alonga diameter of the second surface.

In this context it is, further, preferred when the radial movement andthe oscillating movement are adjusted with respect to each other suchthat the locus of the center of the first surface assumes the shape of amirror-symmetric undulated line during the radial reciprocal movement.

In embodiments of the inventive apparatus one single robot is providedfor handling the glasses between a conveyor, the polishing station, thewashing station and the marking station, wherein the robot is preferablyadapted for executing the polishing process, and, further, the robot isadapted for operating a polishing tool and the washing tool.

These measures have the advantage that all of the movement andprocessing actions are executed by one and the same robot. Insofar, ithas turned out as particularly advantageous when the glasses during therespective processing (polishing and washing) are held by a stationary,however movable holding unit, whereas the robot holds and moves therespective required tool (polishing tool or washing tool).

In this context it is, further, preferred when the robot has a hand,wherein the hand by means of an axial actuator is adapted to bealternately brought into two operational positions, the hand having agripper for gripping a glass and an interface for attaching a tool, thegripper in a first operational position being adapted for gripping andfor depositing a glass, and in a second operational position forgripping and for depositing a tool.

This measure has the advantage that the door-to-door time within theprocessing cell may be further reduced because it is no more required toprovide a special change step for the gripper or the tool holder at thehand of the robot.

In a preferred improvement of this embodiment the axial actuator is arotary actuator.

This measure has the advantage that a particularly simple sequence ofmovements may be obtained in that, for example, the hand rotates by 180°respectively when in one instance a glass shall be handled and inanother instance a tool shall be inserted.

In a preferred improvement of the inventive apparatus which may also beused alone, the robot has a gripper which grips the glasses at theirperiphery. In particular, this is effected with a predetermined force,wherein, further a force controller is preferably provided.

These measures have the already mentioned advantage that the sensitiveoptical surface of the spectacle lens does not need to be touched duringthe gripping of the glasses.

In this context it is particularly preferred when the gripper has threeor more fingers arranged essentially parallel to each other and beingadapted to be brought into engagement with the periphery of a glass.

This measure has the advantage that according to the number and thepositioning of the fingers a gripping function as well as a centeringfunction may be executed, and that the number and type of fingers may beoptimised, depending on whether the glasses to be handled have acircular or an elliptical periphery or are shaped generally otherwise.

According to another preferred variant of this embodiment the fingersare provided with a soft envelope at their periphery.

This measure has the advantage that a damage to the periphery of theglasses is avoided even when relatively high gripping forces are used.

In another preferred embodiment of the invention that may likewise beused alone, for polishing a first surface of a glass a polishing tool isprovided which, one the one hand is tangentially guided with a second,rotating surface over the first surface, and, on the other hand, forcompensating different elevations within the first surface is fed-in ina direction perpendicular to the first surface. Thereby, an element forgenerating the rotation and/or for feeding-in is configured hollow.

This measure has the advantage that the masses which have to be movedduring the polishing process, may be kept very small. When doing so,inertia is reduced and the polishing surface may particularly easilyfollow the surface of the glass to be polished, wherein only minimumforces have to be executed.

Insofar it is particularly preferred when the element is a tube.

This measure has the advantage that a very simple and low-cost elementmay be used.

In a preferred improvement of this embodiment the tube is a polygonaltube being radially journalled by means of roller bearings.

This measure has the advantage that the tube in its axial feedingdirection is journalled almost free of friction because roller bearingsprevent a radial movement of the polygonal tube at lowest possiblefriction.

In a further preferred way the tube transmits a torque from a rotationaldrive to the polishing tool.

For that purpose the tube may be configured as a polygonal tube, asalready mentioned, or may be configured as a non-circular tube or as atube having a spline tooth or the like.

In another improvement of this embodiment the element is connected to alinear displacement unit by means of a spherically journalled, nontorque-transmitting transmission element.

This measure has the advantage that the axial feeding-in movement of thepolishing tool may be executed independently from the transmission oftorque for the rotational movement of the polishing tool. The elementsrequired for the axial displacement are, therefore, decoupled from thetransmission of torque and can be configured with low friction.

Preferably, the linear displacement unit is configured as apiston-cylinder unit.

This measure has the advantage that proven positioning and controlelements can be used.

In this context it is further preferred when the transmission element isa coupling rod being preferably journalled spherically at both ends.

These measures have the advantage that the already mentioned no torquetransmitting connection may be established, wherein the spherical joint,further, prevents that the piston becomes jammed within the cylinder asa consequence of an oblique position of the surface to be polished.

In a further preferred embodiment of the invention which may also beused alone, for polishing a first surface of a glass a polishing tool isprovided which, one the one hand is tangentially guided with a second,rotating surface over the first surface, and, on the other hand, forcompensating different elevations within the first surface is fed-in ina direction perpendicular to the first surface, wherein for feeding-inthe second surface a piston-cylinder unit is provided, thepiston-cylinder unit comprising a piston air-mounted within a cylinder.

This measure has the advantage that a particularly low frictionarrangement is obtained because the piston is guided within the cylindervia an air bearing. As a consequence the contact force of the polishingtool, i.e. the polishing force, may be set particularly sensibly.

In this context it is particularly preferred when the cylinder is aglass cylinder, and that the piston is a graphite piston.

This measure has the advantage that an optimum frictional matching isobtained which may be operated over wide temperature ranges.

Further, a particularly good result is obtained in this context when thepiston-cylinder unit is connected to a working reservoir containingcompressed air and having a first predetermined volume, the pistondefining a second predetermined volume within the cylinder between itsextreme operational positions, the first volume being much bigger thanthe second volume, preferably at least 100 times, in particular at least1,000 times as big as the second volume, and, mostly preferred, when thefirst volume is about 1 cm³ and the second volume is about 3,000 cm³.

This measure has the advantage that the system operates extremelylinearly over the entire working stroke of the piston because the changein volume within the working cylinder is significantly smaller ascompared to the volume within the pressure reservoir.

In another preferred embodiment of the invention which may also be usedalone, for polishing a first surface of a glass a polishing tool isprovided which, one the one hand is tangentially guided with a second,rotating surface over the first surface, and, on the other hand, forcompensating different elevations within the first surface is fed-in ina direction perpendicular to the first surface, wherein for executingthe feeding-in movement a transmission element is provided, thetransmission element being linearly moved relative to a housing andprotruding with a section from an end of the housing in an oscillatingmanner, a first bellows being arranged between the end and the section.

This measure has the advantage that the transmission element, moved inoscillation, is best protected against the intrusion of dirt. This is ofparticular advantage for the present application because during thepolishing of the surface of the glass a substantial soiling occurs suchthat the guiding of the oscillating transmission element couldeventually become clogged with the wear of the polishing tools.

In a particularly preferred practical example of this embodiment thesection carries an annular flange, the first bellows connecting theflange with the end.

This measure has the advantage that a particularly simple andmechanically reliable setup is obtained.

In another preferred embodiment of the invention which may likewise beused alone, for polishing a first surface of a glass a polishing tool isprovided which, one the one hand is tangentially guided with a second,rotating surface over the first surface, and, on the other hand, forcompensating different elevations within the first surface is fed-in ina direction perpendicular to the first surface, wherein for executingthe feeding-in movement a transmission element is provided, thetransmission element being linearly moved relative to a housing andprotruding with a section from an end of the housing in an oscillatingmanner, the section being surrounded by a protective sleeve beingconnected to the housing.

This measure has the advantage that an unintended damage to theoscillating protruding section of the transmission element is definitelyprevented.

If, in a preferred improvement of this embodiment the protective sleevesurrounds the first bellows, this protection function extends also tothe first bellows.

In still another embodiment of the invention that may likewise be usedalone, for polishing a first surface of a glass a polishing tool isprovided which, one the one hand is tangentially guided with a second,rotating surface over the first surface, and, on the other hand, forcompensating different elevations within the first surface is fed-in ina direction perpendicular to the first surface, wherein the polishingtool is pivotably journalled in a transmission element, the transmissionelement being movable in the feeding-in direction along an axis, atumbling disk being provided, the tumbling disk being connected with thetransmission element via a spherical joint, and the tumbling disk beingadapted to be coupled to the polishing tool.

This measure has the advantage that the spherically journalled tumblingdisk enables in a particularly perfect manner to follow the differentelevation of the surface to be polished of the glass. This holds true inparticular in comparison to the gimballed suspensions of the prior art(U.S. Pat. No. 5,247,999) and, in particular, a bearing by means of aroller bellows (EP 0 567 894 A1), but also in comparison to a sphericalAllen joint (WO 01/56740 A1, DE 101 00 860 A1).

In connection with the afore-described embodiment of the invention it ispreferred when the transmission element has a ball head as a terminalend, the polishing tool being provided with a ball socket, the polishingtool being elastically held on the transmission element, wherein theball head is elastically held in the ball socket, such that thepolishing tool can execute a tumbling movement relative to thetransmission element.

This measure has the advantage that, one the one hand, a tumblingmovement of the polishing tool is possible and, on the other hand, bymeans of the elastic support the necessary torque can be transmitted tothe polishing tool, while at the same time the spherical joint is heldaltogether with the necessary bearing force.

In a preferred improvement of this embodiment, the transmission elementhas a finger as an axial terminal end, the ball head being arranged at afree end of the finger.

This measure has the advantage that due to the cantilevered arrangementof the spherical joint consisting of the ball head and the ball socket atumbling movement with a particularly large amplitude is enabled.

Further, in this embodiment it is preferred when for elastically holdingthe polishing tool a second, torque-transmitting bellows is arrangedbetween the transmission element and the polishing tool.

This measure, on the one hand, has the advantage that the sphericaljoint in the above-described manner is also reliably protected againstsoiling as occurs during the polishing process; on the other hand, theelastic support and, thereby, the transmission of torque as well as theholding force within the spherical joint may be guaranteed with aparticularly simple and low cost element, namely a bellows.

This holds true in a preferred manner if the second bellows surroundsthe finger.

Finally it is preferred in this context if the ball socket is configuredconical.

This measure has the advantage that there only exists a very smallcontact surface between the ball head and the ball socket, ideally justa contact line, such that the joint has only a very low friction.

In a preferred embodiment of the invention which may also be used alone,for polishing a first surface of a glass a polishing tool is provided,the polishing tool being coupled to a drive via a magnetic clutch.

This measure has the advantage that no mechanical clutch has to beopened or closed for connecting the polishing tool with its drive.Instead, the magnetic clutch may be opened and closed in a simplemanner. This may be done either electrically, or by separating themagnetically coupled elements from each other through the application ofa pulling force.

In a preferred improvement of this embodiment the magnetic clutch isprovided with permanent magnets.

This measure has the advantage that the clutch is operated withoutcurrent. The permanent magnets may either be used as a pair of permanentmagnets or as a permanent magnet together with a corresponding piece ofsoft iron.

In this embodiment an example is further preferred in which thepolishing tool, on the one hand, is tangentially guided with a second,rotating surface over the first surface, and, on the other hand, forcompensating different elevations within the first surface is fed-in ina direction perpendicular to the first surface, wherein the polishingtool is pivotably journalled in a transmission element, the transmissionelement being movable in the feeding-in direction along an axis, atumbling disk being provided, the tumbling disk being connected with thetransmission element via a spherical joint, and the tumbling disk beingadapted to be coupled to the polishing tool via a magnetic clutch.

This measure has the advantage that in a practical embodiment thepolishing tool may, in a most simple manner, be coupled to and decoupledfrom its corresponding drive unit, namely the tumbling disk, such thatthe polishing tool needs only to consist of a polishing disk and apolishing coating.

Also in the afore-mentioned case it is preferred when the transmissionelement has a ball head as a terminal end, the polishing tool beingprovided with a ball socket, and the polishing tool being elasticallyheld on the transmission element, wherein the ball head is elasticallyheld in the ball socket, such that the polishing tool can execute atumbling movement relative to the transmission element.

In another group of embodiments of the invention that may likewise beused alone, a tool magazine is provided, a plurality of polishing toolsbeing deposited in the tool magazine, the tool magazine being locatedwithin the operational area of a robot.

This measure has the advantage that the tool change, in particular thepolishing tool change, may be automated. In particular, a worn polishingtool may be exchanged against a fresh polishing tool. Further, it ispossible for the subsequent processing of glasses of different size tochange polishing tools in different sizes one after the other.

In a preferred manner the tool magazine is configured with a pluralityof chutes, the polishing tools being sorted and stored in the chutesaccording to the radii of their polishing surface.

Further, it is preferred when the chutes are inclined relative to ahorizontal plane, and when slideways for the polishing tools areprovided.

This measure has the advantage that the tools move up sliding in thechutes as soon as a tool is withdrawn at the lower end such that a newtool is automatically placed ready every time at a pickup positionwithout the necessity of separate conveyor installations.

In that case it is preferred when stops are provided at the lower end ofthe slideways.

Further advantages of the invention will become apparent from thedescription and the appended drawing.

It goes without saying that the features mentioned above and those thatwill be explained hereinafter may not only be used in the particularlygiven combination, but also in other combinations, or alone, withoutleaving the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are shown in the drawing and will beexplained in the subsequent description.

FIG. 1 shows a flow chart for explaining a method for producing opticalglasses according to the prior art;

FIG. 2 shows a flow chart, similar to FIG. 1, however, for an embodimentof a method according to the present invention;

FIG. 3 shows a highly schematic top plan view of an embodiment of anapparatus according to the present invention;

FIG. 4 shows a side elevational view along line IV-IV in FIG. 3;

FIG. 5 on a highly enlarged scale shows a side elevational view,partially cut away, of a hand of a robot, as may be used in an apparatusaccording to FIGS. 3 and 4;

FIG. 6 on a further enlarged scale shows a portion of the hand of FIG. 5for explaining further details;

FIG. 7 on a further enlarged scale shows a detail from FIG. 6 depictingan air cylinder;

FIG. 8 on a further enlarged scale shows a detail illustration of FIG.6, depicting a tumbling disk;

FIG. 9 on a further enlarged scale shows a detail from FIG. 6 depictinga polishing tool;

FIGS. 10 and 11 show two perspective views of the elements tumbling diskand polishing tool depicted in FIGS. 8 and 9;

FIG. 12 shows a schematic side elevational view, partially cut away, ofa gripper as may be used in the hand of the robot according to FIG. 5;

FIGS. 13 through 17 show schematic top plan views on the arrangement ofFIG. 12, for five distinct embodiments;

FIG. 18 shows a highly schematic side elevational view of a toolmagazine as may be used with an apparatus according to FIGS. 3 and 4;

FIG. 19 shows a top plan view on the tool magazine according to FIG. 18;

FIG. 20 shows a sectional view along line XX-XX of FIG. 19;

FIG. 21 on a highly enlarged scale shows a top plan view on a glassbeing processed according to the method of the present invention; and

FIG. 22 shows a detailed flow chart for explaining the process accordingto the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In FIG. 1 reference numeral 10 as a whole indicates a flow chart forexplaining a working process according to the prior art. After thelathing or the grinding of a spectacle lens (block 12) the spectaclelens as well as a polishing tool are manually fed to a polishing machine(block 14). The polishing machine then executes the polishing process(block 16). The polished spectacle lens is then unloaded and thepolishing tool is removed (block 18).

The spectacle lens must now be cleaned manually or by means of a specialwashing device (block 20), and the polishing tool and/or the washingtool must be reprocessed manually or by means of a special device (block22). The spectacle lens is then manually fed to a marking station (block24) and marked therein (block 26). Only then the spectacle lens may beunloaded by hand (block 28) and may be transported away.

From the preceding description it becomes apparent that the conventionalprocesses require a substantial amount of time because a large number ofmanual steps have to be executed which costs time on the one hand andmay be a source of faults, on the other hand.

In contrast thereto, FIG. 2 shows a block diagram 30 which, in aconventional manner, follows the automatic shaping process of thespectacle lens by lathing or grinding (block 32), whereas thereafter allsubsequent steps of polishing, cleaning and marking are executed fullyautomatically (block 34), without the necessity of manual intervention.This shall be described hereinafter:

In FIGS. 3 and 4 reference numeral 40 designates a processing cellhaving a housing frame 41. The processes of polishing, washing andmarking are executed fully automatically within processing cell 40.

The lenses are fed from a conventional lathing or grinding machine 42 toa conveyor belt 44 in the direction of an arrow 43, where they aretransported to processing cell 40 along a conveyor direction indicatedby an arrow 46.

Transportation boxes 48 are used for transportation on conveyor belt 44.Each of transportation boxes 48 receives one pair of lenses 50 a, 50 b,being each allotted to a particular patient or customer. As will beexplained further below (FIG. 12), lenses 50 are arranged on a block 51,as known per se, so that they may be easier held and moved (rotated)during processing.

In the embodiment shown, four handling positions 52 a, 52 b, 52 c and 52d are indicated on conveyor belt 44 within processing cell 40. At thesehandling positions 52 a through 52 d, one transportation box 48 may bestopped at one time. This makes it possible to place lenses 50 ready ina predetermined position, so that lenses 50 from differenttransportation boxes 48 may be processed in parallel within differentstations of processing cell 40.

Processing cell 40 comprises a polishing station 54, a washing station56, a marking station 58 as well as a central control unit 60. A robot62 is provided within processing cell 40 as a central work unit. Robot62 cooperates with a tool magazine 64.

Robot 60 is standing on a base 70. Various possible movements of robot60 are indicated by arrows 72 and 74. In a preferred embodiment of theinvention, robot 62 is a six-arm-robot.

Robot 62 is provided with an arm 76 having a hand 78 at a free endthereof. Hand 78 is adapted to be rotated about an axis 80 extendingalong arm 76, as indicated with another arrow 82.

Processing cell 40 operates as follows:

At the beginning of a processing operation robot 62 is actuated suchthat a gripper arranged on arm 78 takes a lens 50 out of atransportation box 48. Details of the gripper will be explained furtherbelow with regard to FIGS. 5 and 12 through 17.

Robot 62 now transfers lens 50 to a polishing spindle 84 withinpolishing station 54. Lens 50 with its block 51 is inserted into asocket of polishing spindle 84, such that lens 50 may be rotated.

After depositing lens 50 within polishing spindle 84, robot 62 driveshand 78 to tool magazine 64. There, polishing tools 88 are stored inchutes 86. For example, polishing tools 88 of different size may besorted in different chutes 86. Further details of tool magazine 64 willbe explained further below with regard to FIGS. 18 through 20.

As polishing tools 88 are wearing parts requiring to be reprocessedafter a polishing process, it is necessary to keep available asufficient large number of polishing tools 88 within tool magazine 64,for example as many polishing tools as are needed for a one dayproduction.

For receiving polishing tool 88, hand 78 of robot 62 is rotated aboutaxis 80 so that the respective polishing tool 88 may be received.Details thereof will be explained further below with regard to FIGS. 5through 11.

Robot 62 with polishing tool 88 arranged at hand 78 now returns topolishing station 84 and moves into a collar surrounding polishingspindle 88 until polishing tool 88 with its polishing surface comes intocontact with the surface of lens 50 to be polished. Details of thepolishing process will be described further below, in particular withregard to FIG. 21.

As soon as the polishing process is completed, hand 78 with polishingtool 88 moves out of polishing spindle 84. Polishing tool 88 is nowtransferred to a dumping magazine 90. Here, polishing tool 88 isstripped from hand 78 by driving polishing tool 88 forward behind acut-back stop and by then retracting hand 78 back from polishing tool88. Polishing tool 88 then falls into a container within dumpingmagazine 90 filled with a cleaning fluid.

Robot 62 now returns with hand 78 to polishing station 54 and takes lens50 having been polished but being soiled due to the preceding polishingprocess. It now transfers same to washing station 56, namely into aholder 94 being located there.

Robot 62 now separates with its hand 78 from lens 50 an picks up asponge 98 arranged in a trough 96 of washing station 56 for cleaningpolished lens 50 thereafter. For that purpose lens 50 may remain securedstationarily or may be moved within holder 94.

After the completion of the washing process sponge 98 is again depositedin a deposition unit 100 of trough 96. Again, this may be effected bymeans of a cut-back stop and a stripping movement of the hand.

For supporting the washing process a plurality of jets is provided, oneof which being indicated at 102 in FIG. 4. A washing fluid, for examplewater, and subsequently a drying medium, for example compressed air, maybe fed via jets 102.

After having deposited sponge 98 robot 62 with its hand 78 again movesto lens 50 having now been washed an dried and takes it from holder 94.Robot 62 now transfers lens 50 to a marking holder 104 within markingstation 58. Lens 50 is marked there, for example by means of a laser,i.e. is provided with a certain product number, but may also be providedwith marks on the optical surface allowing the optometrist at a laterstage to exactly fit the spectacle lens into a spectacle frame.

While within the polishing station as well as within the washingstation, robot 62 actively participated in the processing steps ofpolishing and of washing executed therein, such activity is not requiredwithin marking station 58 because lens 50 was only deposited in markingholder 104, whereas the marking itself is executed automatically andwithout the involvement of robot 62.

Considering that the marking process on the other hand side requiressome time, robot 62, in a preferred improvement of the invention, mayalready take the subsequent lens 50 from its transportation box 48during that time and may execute the afore-described steps of polishingand of washing thereon. It may also be possible to likewise handle andprocess the next but one lens accordingly, until the marking on thefirst lens is completed whereupon it may be taken away from the markingholder by robot 62 and be laid back into its transportation box 48.

Transportation boxes 48 with the completely processed lenses 50 nowleave processing cell 40 on conveyor band 44 in the direction of arrow106 indicated in FIG. 3.

FIGS. 5 through 17 show further details of elements arranged on hand 78.

FIG. 5 in a side elevational view shows the axis 80 of arm 76 extendingperpendicular to FIG. 6 as well as the pivotal movement of hand 78 by,preferably 180° each, indicated with arrow 82. At this point it shouldbe self-understanding that hand 78 may also be provided with a largernumber of units at respective smaller angular increments.

In the illustration of FIG. 5 a gripper 110 with a plurality of fingers112 is arranged at the upper end of hand 78. At the lower end of hand 78a polishing head 114 together with a rotational drive 116 for polishingtool 88 as well as a piston-cylinder unit 118 for an axial displacementof polishing tool 88 along a longitudinal axis 120 are provided.

Also at this point it goes without saying that the elements shown are tobe understood only schematically and that of course other types ofrotary drives or of linear drives may likewise be used.

FIG. 6, on an enlarged scale and with further details, shows the lowerend of hand 78. This lower end is entirely surrounded by a housing 128.

Within housing 128 and below rotary drive 116 there is arranged a firstpinion 130 driven thereby, connected with a second pinion 132 via atoothed belt 134, the second pinion 132 rotating about axis 120. Secondpinion 132 drives a rotor 136 being journalled via a plurality ofbearings within a seat 137 being stationary with the housing.

At its lower end rotor 136 is provided with a sleeve 138 in which apolygonal tube 140 is arranged non-rotatably but axially displaceable.Polygonal tube 140 is radially journalled within sleeve 138 via rollerbearings 142. As a consequence, polygonal tube 140 rotates with sleeve138, however, may axially move within sleeve 138 with almost nofriction.

Rotor 136 terminates downwardly in a lower end 142 and configures aradial closure plane there. A tapering section 145 of polygonal tube 140extends through the closure plane and protrudes outwardly. At the freeend thereof a tumbling disk 144 is arranged, further details of whichbeing explained below with regard to FIG. 8.

A first bellows 146 is attached with its upper rim to the lower end 143of rotor 136 and with its lower rim to a flange 147 surrounding thelower portion of protruding section 145 of polygonal tube 140. Therebyit is effected that during an axial movement of section 145, within theopening defined by lower end 143, no dirt may enter from outside intothe area of the polygonal tube 140, and, in particular, not into thearea of roller bearings 142.

Finally, a surrounding protective sleeve 148 is arranged about firstbellows 146.

Polygonal tube 140 may be displaced in the direction of axis 120according to a predetermined force/displacement function.Piston-cylinder unit 118, already mentioned, is used for that purpose.

Piston-cylinder unit 118 is preferably operated pneumatically. For thatpurpose, a rotary compressed air junction 150 is provided at the upperend of piston-cylinder unit 118 allowing a compressed air supply topiston-cylinder unit 118 rotating during operation together with rotor136. A duct 152 connects rotary joint 150 to a compressed air reservoir154. In FIG. 6, the volume thereof is designated with V_(R) and itsoperating pressure with p_(R).

Piston-cylinder unit 118 is provided with a so-called air cylinder 160.As can particularly be seen from FIG. 7, air cylinder 160 is providedwith a glass cylinder 162, within which runs a piston 164 with minimumair gap 166. An axial force-transmitting connection is establishedbetween piston 164 and an upper flange 172 of polygonal tube 140 via acoupling rod 168, the upper and the lower end of which being providedwith a ball head, the upper end being designated 170 in FIG. 7.

In a practical embodiment piston 164 has a diameter of 16 mm and astroke of 5 mm. The working volume of piston 164 between its extremeoperational positions, designated V_(A) in FIG. 7 is, therefore, about 1cm³.

Volume V_(R) of compressed air reservoir 154, in contrast, is about3,000 cm³, such that the ratio of the volumina in that case is 3,000:1.The operational pressure p_(R) is, for example, between 4 and 5 bar.Thereby, an operational force of piston 164 in the range of between 50and 100 N is generated.

Cylinder 162, as already mentioned, preferably consists of glass. Piston164 preferably consists of graphite, whereby an optimum frictionalmatching is generated, resulting in a minimum frictional coefficientover wide ranges of temperature. Due to the small air gap 166 an airbearing between piston 164 and cylinder 162 is configured, such thatpiston 164 runs within glass cylinder 162 with almost no friction.

By means of rotary drive 116 a rotary movement of rotor 136 at, forexample 1,000 min⁻¹ is induced. In order to enable polishing tool 88with the lower side of tumbling disk 144 to follow the change ofelevation of lens 50 rotating at the same speed and, preferably, withthe same direction of rotation, polishing tool 88 follows the rotatingspectacle lens surface with a constant contact force at frequenciesabove 50 Hz.

The low friction of the elements responsible for the linear drivetogether with the small weight, in particular that of hollow polygonaltube 140, enables a precise position control at extremely small inertialforces.

FIG. 8 shows further details of tumbling disk 144.

A lower end 180 of section 145 of polygonal tube 140 terminates in afirst disk 182 which, as a clamping device, is provided with an upperplate 183 a and a lower plate 183 b which can be bolted together. Anupper rim 184 of a second bellows 186 is clamped between these plates183 a, 183 b, the second bellows 186, like first bellows 146, beingarranged rotationally symmetrical about axis 120.

A lower rim 188 of second bellows 186 is held in a second disk 190 whichis likewise configured as a clamping device with an upper plate 191 aand a lower plate 191 b.

Second bellows 186 surrounds a spherical joint. The spherical joint isconfigured, on the one hand, by an axial finger 192 extending downwardlyas an extension of lower end 180, and having at its free end 180 a ballhead 194 with a center 196.

The counterpart of the spherical joint is configured by a conicalopening 198 within upper plate 191 a as well as a ball socket 200 withinlower plate 191 b. Ball socket 200, preferably, is configured as a conewithin an insert 202 within lower plate 191 b.

As can easily be seen from FIG. 8, second disk 190 may execute atumbling movement relative to first disk 182, during which ball socket200 is pivoted about ball head 194.

Second bellows 186, insofar, has three functions:

On the one hand, second bellows 186 is adapted to transmit a torque frompolygonal tube 140 via the lower end 180 of the latter to second disk190 to which polishing tool 88 is attached, as will still be explained.

On the other hand, second bellows 186 generates an axially directedpulling force, pulling second disk 190 elastically upwardly, such thatball head 194 is elastically held within ball socket 200. In such a way,second disk 190 may execute a tumbling movement relative to first disk182 over a wide angular range.

Finally, second bellows 186 acts as a protection of the spherical jointagainst being soiled.

In order to be able to attach polishing tool 88 to tumbling disk 144from below, the following measures have been taken:

First, on the lower side of second disk 190 a pin 204 is providedprotruding along axis 120 and being provided with a taper 206 at itslower end. Second, the lower side of second disk 190 is provided withthree permanent magnets 208 a, 208 b, and 208 c, offset about 120° withrespect to each other in a peripheral direction, as becomes particularlyapparent from FIG. 11.

FIG. 9 shows that polishing tool 88 has a third disk 210 being providedwith an annular flange 211 at its periphery, as will be discussed belowin connection with the explanation of the tool magazine (FIGS. 18through 20).

Below third disk 210 there is an elastic layer 212, preferably a softsponge. The tool 214 as such is attached to the underside of layer 212and is commonly referred to as polishing shell. The lower surface 216thereof, constituting the polishing surface, is shaped convex in theembodiment shown in FIG. 9 in order to polish concave lens surfaces. Ofcourse, surface 216 may also be shaped convex for processing concavelens surfaces.

A location hole 218 is located in the center of third disk 210, hole 218being complementary to pin 204 of tumbling disk 144. In particular, hole218 has an insertion taper at its upper end adapted to cooperate withtaper 206 of pin 204.

Further, third plate 210 is likewise provided with three permanentmagnets 222 a, 222 b, t 222 c spaced by 180° with respect to each other,as can most clearly be seen in FIG. 10.

As can be easily understood, polishing tool 88 may be simply connectedwith tumbling disk 144 by assembling axially the elements shown in FIGS.8 and 9. Then pin 204 enters into hole 218 and magnets 208/222 attracteach other and provide for the necessary holding force. In theillustrated embodiment, magnets 208/222, further, are configured ascatches, such that there is also a torque-transmitting connectionbetween tumbling disk 144 and polishing tool 88 because magnets 222enter into bores 224 into which magnets 208 are inserted.

It should be clear at this point that permanent magnets 208, 222 are tobe understood solely as examples. Electrically operated magnets orcombinations of magnets and of soft iron parts could likewise be usedwith the same results.

FIGS. 12 and 17 illustrate further details of gripper 110.

FIG. 12 shows that fingers 112 of gripper 110 consist of a core 230 andof an envelope 232, wherein core 230 is configured mechanically stableand hard, whereas envelope 232, preferably, is configured soft.

It is important for gripper 110 that fingers 112 grip lens 50 solely atits periphery 236, whereby, in contrast to the prior art, the opticalsurface of lens 50 remains untouched.

FIG. 13 shows a configuration in which a lens being circular in a topplan view is held by four fingers 112 a through 112 d which, accordingto FIG. 14 is also possible for a lens with an elliptical shape as seenfrom above.

As illustrated by FIGS. 15 and 16, this is likewise possible if threefingers 112 a through 112 c are used.

Finally, FIG. 17 shows an irregularly shaped lens 50′, as seen fromabove, which may also be held by three fingers.

FIGS. 18 through 20 illustrate further details of tool magazine 64.

Tool magazine 64 is provided with two parallel rails 240 a, 240 b foreach chute 86. Rails 240 a, 240 b are each provided with longitudinallyextending slide grooves 242 a, 242 b facing each other. At the left handend of grooves 242 a, 242 b, as seen in FIGS. 18 and 19, spring-biasedpins 244 a, 244 b are provided which, in their relaxed state extend intoslide grooves 242 a, 242 b.

Rails 240 a, 240 b are arranged in an inclined orientation relative to ahorizontal mount 246, as indicated in FIG. 18 by an angle α.

Polishing tools 88 are held within rails 240 a, 240 b, by lettingabove-mentioned annular flanges 211 of third disks 210 of polishingtools 88 run in slide grooves 242 a, 242 b (cf. FIG. 9). Under theaction of gravity, polishing tools slide by themselves to the left handend of rails 240 a, 240 b, as seen in FIG. 18. The respective lowermostpolishing tool 88 is retained there by means of spring-biased pins 244a, 244 b.

As can clearly be seen from FIGS. 8 and 9, second disk 190 at the lowerend of tumbling disk 144 has a much smaller diameter as compared tothird disk 210 at the upper side of polishing tool 88 which is alsoshown from above in FIG. 19. Robot 62, therefore, in the operationalposition of FIG. 5, may move with its hand 78 into the area of toolmagazine 64 and insert second disk 190 into the gap between rails 240 aand 240 b until second disk 190 comes to rest on third disk 210,whereupon disks 190, 210 stick together under the action of magnets 208,222. Robot 62 may now displace hand 78 in an axial direction of therespective chute 86, such that the respective foremost polishing toolovercomes the retaining force of spring-biased pins 244 a, 244 b and ispulled out of slide grooves 242 a, 242 b. Thereupon, under the action ofgravity, the respective next polishing tool 88 moves up by sliding.

FIG. 21 shows a spectacle lens surface 250 in the manner of a polarcoordinate system. The principal axes are designated x and y.

An arrow 252 indicates the direction or rotation of lens 50, and, hence,of surface 250 when lens 50 is positioned within polishing spindle 84 ofpolishing station 54.

In FIG. 21 surface 216 of polishing tool 88 is also shown as it rests onspectacle lens surface 250. The center of surface 216 is designated 254.Polishing surface 216 rotates in the same direction as spectacle lenssurface 250 as indicated by an arrow 258. The rotational speeds arelikewise essentially the same.

Reference numeral 256 in FIG. 21 indicates a locus of movement of center254 of polishing surface 216 during the inventive polishing process.

As can clearly be seen, locus 256 is generated by the superimposition oftwo periodical movements. The first movement runs along a diameter 260of spectacle lens surface 250, i.e. in the y-direction in theillustration of FIG. 21. A second movement is superimposed on the firstmovement, wherein the second movement oscillates in the x-direction withsmall amplitude. The ratio between the frequencies of these movements inthe y-direction and in the x-direction is 1:3 in the illustratedembodiment. Thus, a mirror-symmetrical undulated line instead of thestraight line in equidistant distances according to the prior art.

Finally, FIG. 22 shows a third flow chart 270, again illustrating theafore-described sequential steps within processing cell 40. Accordingly,the lenses 50 arranged on blocks within transportation boxes 48 areprocessed according to the following scheme:

if marking station 58 is not free, transport marked lens 50 back intoits transportation box 48

if washing station 56 is free, transport washed lens 50 into markingstation 58

if polishing station 54 is free, transport polished lens 50 into washingstation 56

if there is an unprocessed lens 50, transport lens 50 into polishingstation 54

if there is a finished transportation box 48, start conveyor belt 44

if not, go to polishing

if a transportation box 48 is found, then compute the polishing processas well as the polishing tool 88 individually for the right lens 50 andfor the left lens 50 and check whether there is a polishing tool 88within tool magazine 64

if no new transportation box is found, activate the start function

if start is pushed, then go to polishing

if polishing station 54 is not free, polish lens 50 according to thecomputed program (getting polishing tool 88, polishing, depositingpolishing tool 88 in dumping magazine 90)

if marking station 58 is not free, then mark lens 50 according to thepredetermined data

after the polishing transport lens 50 into washing station 56

wash lens 50

go to program start.

1. An apparatus for producing optical glasses, comprising a polishingtool having a first, rotating surface, means for tangentially guidingsaid first surface over a second surface of said glasses, means forfeeding-in said first surface in a direction perpendicular to saidsecond surface for compensating different elevations within said secondsurface, said means for feeding-in comprising a hollow element, saidelement being adapted to be fed-in within a sleeve, said sleeve beingdriven in rotation and fixed axially, wherein, further, said element isconnected to said sleeve such as to transmit torque and has a free endsection protruding from said sleeve and being connected to saidpolishing tool.
 2. The apparatus of claim 1, wherein said element is atube.
 3. The apparatus of claim 2, wherein said tube is a polygonaltube, said polygonal tube being radially journalled by means of rollerbearings.
 4. The apparatus of claim 1, wherein said element is connectedto a linear displacement unit by means of a spherically journalled, nontorque-transmitting transmission element.
 5. The apparatus of claim 4,wherein said linear displacement unit is configured as a piston-cylinderunit.
 6. The apparatus of claim 4, wherein said transmission element isa coupling rod.
 7. The apparatus of claim 6, wherein said coupling rodis spherically journalled at both ends.
 8. The apparatus of claim 5,wherein said means for feeding-in comprise a piston-cylinder unit, saidpiston-cylinder unit comprising a piston air-mounted within a cylinder.9. The apparatus of claim 8, wherein said cylinder is a glass cylinder,and said piston is a graphite piston.
 10. The apparatus of claim 8,wherein said piston-cylinder unit is connected to a working reservoircontaining compressed air and having a first predetermined volume, saidpiston defining a second predetermined volume within said cylinderbetween its extreme operational positions, said first volume being muchbigger than said second volume.
 11. The apparatus of claim 10, whereinsaid first volume is at least 100 times as big as said second volume.12. The apparatus of claim 10, wherein said first volume is at least1,000 times as big as said second volume.
 13. The apparatus of claim 12,wherein said first volume is essentially 1 cm³ and said second volume isessentially 3,000 cm³.
 14. The apparatus of claim 1, wherein saidsleeve, for executing said feeding-in movement, in operation protrudeswith a section carrying said polishing tool from an end of a housing inan oscillating manner, wherein, further, a first bellows is arrangedbetween said end and said section.
 15. The apparatus of claim 14,wherein said section carries an annular flange, said first bellowsconnecting said flange with said end.
 16. The apparatus of claim 1,wherein said sleeve, for executing said feeding-in movement, inoperation protrudes with a section carrying said polishing tool from anend of a housing in an oscillating manner, wherein, further, saidsection is surrounded by a protective sleeve being connected to thehousing.
 17. The apparatus of claim 1, wherein said sleeve, forexecuting said feeding-in movement, in operation protrudes with asection carrying said polishing tool from an end of a housing in anoscillating manner, wherein, further, a first bellows is arrangedbetween said end and said section, said section is surrounded by aprotective sleeve being connected to the housing, and said protectivesleeve surrounds said first bellows.
 18. The apparatus of claim 1,wherein said polishing tool is pivotably journalled in a transmissionelement, said transmission element being movable in said feeding-indirection along an axis, a tumbling disk being provided, said tumblingdisk being connected with said transmission element via a sphericaljoint, and said tumbling disk being adapted to be coupled to saidpolishing tool.
 19. The apparatus of claim 18, wherein said transmissionelement has a ball head as a terminal end, said polishing tool isprovided with a ball socket, and said polishing tool is elastically heldon said transmission element, wherein, further, said ball head iselastically held in said ball socket, such that said polishing tool canexecute a tumbling movement relative to said transmission element. 20.The apparatus of claim 19, wherein said transmission element has afinger as an axial terminal end, said ball head being arranged at a freeend of said finger.
 21. The apparatus of claim 20, wherein forelastically holding said polishing tool a second, torque-transmittingbellows is arranged between said transmission element and said polishingtool.
 22. The apparatus of claim 21, wherein said second bellowssurrounds said finger.
 23. The apparatus of claim 19, wherein said ballsocket is configured conical.
 24. The apparatus of claim 1, wherein saidpolishing tool is coupled to a drive via a magnetic clutch.
 25. Theapparatus of claim 24, wherein said magnetic clutch is provided withpermanent magnets.
 26. The apparatus of claim 24, wherein said polishingtool is pivotably journalled in a transmission element, saidtransmission element being movable in said feeding-in direction along anaxis, wherein, further, a tumbling disk is provided, said tumbling diskbeing connected with said transmission element via a spherical joint,and said tumbling disk being adapted to be coupled to said polishingtool via a magnetic clutch.
 27. The apparatus of claim 26, wherein saidtransmission element has a ball head as a terminal end, said polishingtool being provided with a ball socket, and said polishing tool beingelastically held on said transmission element, wherein said ball head iselastically held in said ball socket, such that said polishing tool canexecute a tumbling movement relative to said transmission element.